Purification of fat body glutathione S‐transferase from the desert locust Schistocerca gregaria: investigation of flavonoid inhibitory effects on enzyme activity

Focus on the development of botanical insecticides such as polyphenols may represent an alternative method to chemical control. In the present study, total glutathione concentration and its related antioxidant enzymes in foregut, midgut, hindgut and fat body homogenates of the desert locust Schistocerca gregaria are examined. Glutathione S‐transferase (GST) activity exhibits a significantly higher value in fat bodies compared with other tissues. A simple and reproducible procedure for the purification of S. gregaria fat body GST is established and the purified enzyme is shown to be homogenous. The purified GST displays a typical Michaelis behaviour with respect to its substrates. Characterization of the GST, including optimum pH, substrate specificity and inhibitor effects, is carried out. The ability of some flavonoids to inhibit S. gregaria fat body GST activity is examined. High‐performance liquid chromatography analysis indicates that the major components in Glycyrrhiza glabra roots are 18α‐glycyrrhetinic acid, quercetin and rutin, and the major components in Hibiscus sabdariffa calyx are cyanidin 3‐O‐glucoside chloride and delphinidin. Quercetin and delphinidin chloride exhibit strong GST inhibition and the inhibition type is determined for both. Rutin shows a smaller inhibitory effect, whereas 18α‐glycyrrhetinic acid and cyanidin have no effect. Inhibition of S. gregaria fat body GST activity would be expected to prevent, or at least delay, the development of resistance to chemical pesticides. Among the examined levels of the antioxidant enzymes, total glutathione concentration and its related enzymes in foregut, midgut, hindgut and fat body crude homogenates of S. gregaria GST activity exhibit a significantly higher value in fat bodies compared with other tissues. Some flavonoids that are detected in H. sabdariffa calyx and G. glabra root extracts are the most effective inhibitors of the purified S. gregaria fat body GST activity. Inhibition of S. gregaria fat body GST activity by quercetin and delphinidin (major compounds detected by HPLC) would be expected to prevent, or at least delay, the development of resistance to chemical pesticides.     

Discrete limbal epithelial stem cell populations mediate corneal homeostasis and wound healing

1. Download : Download high-res image (160KB)
2. Download : Download full-size image

     

Neuroectodermal stem cells: A remyelinating potential in acute compressed spinal cord injury in rat model

The outcomes of compressed spinal cord injury (CSCI) necessitate radical treatment. The therapeutic potential of neuroectodermal stem cells (NESCs) in a rat model of CSCI in acute and subacute stages was assessed. White Wistar rat were divided into control, sham-operated, CSCI untreated model, CSCI grafted with NESCs at 1 day after CSCI, and at 7 days after CSCI. Primary NESC cultures were prepared from brains of embryonic day 10 (E10) mice embryos. NESCs were transplanted at the site of injury using a Hamilton syringe. Locomotor functional assessment, routine histopathology, immunostaining for (GFAP), and ultrastructure techniques for evaluating the CSI were conducted. In CSCI, areas of hemorrhage, cavitation, reactive astrocytosis, upregulated GFAP expression of immunostained areas, degeneration of the axoplasm and demyelination were observed. One day after grafting with NESCs, a decrease in astrocyte reaction and pathological features, quantitative and qualitative enhancement of remyelination and improved locomotor activity were observed. Treatment with NESCs at 7 days after CSCI did not mitigatethe reactive astrocytosis and glial scar formation that hindered the ability of the NESCs to enhance remyelination of axons. In conclusion, the microenvironment and time of NESCs transplantation affect activity of astrocytes and remyelination of axons.     

Phenotype of apoptotic lymphocytes in children with Down syndrome

Background  

Down syndrome (DS) is the most common and best-known chromosomal disorder and is associated with several other pathologic conditions including immunodeficiency which makes a significant contribution to morbidity and mortality. Various immunological theories and observations to explain the predisposition of individuals with DS to various infections have been published, one of which is increased apoptotic cells.